1. Field of the Invention
The present invention relates to a shell for drum such as a bass drum, a snare drum, and a marching drum, and a drum using the same.
Priority is claimed on Japanese Patent Application No. 2008-002220, filed Jan. 9, 2008, the content of which is incorporated herein by reference.
2. Description of Related Art
A shell which a drum head of a drum is provided over in a tensioned state is normally made from various materials such as wood, metal such as aluminum alloy, and fiber reinforced plastic (FRP) (see for example Japanese Unexamined Patent Application, First Publication No. H11-45087, Japanese Patent Publication No. 3324577 {Japanese Unexamined Patent Application, First Publication No. 2001-67066}, and Japanese Examined Utility Model Application, Second Publication No. S53-47939). Most shells are made from wood, since this obtains a musically warm sound.
A wood of appropriate hardness and superior acoustical characteristics is used, e.g. maple, birch, beech, or bamboo.
A shell of a Japanese drum disclosed in Japanese Unexamined Patent Application, First Publication No. H11-45087 is made from a wooden material or a non-wooden material for the shell and has a polygonal shape. As the wooden material, a particle board, a fire board, bonded wood, laminated wood, plywood, or another material, are used. As the non-wooden material, synthetic resin material, glass fiber-filled resin material, carbon fiber-filled resin material, boron fiber-filled resin material, a compound material made by selectively using some of these materials, or another material, are used.
A shell of a drum disclosed in Japanese Patent Publication No. 3324577 is formed as follows. A joined plate is obtained by joining a plurality of elongated flat-plate-shaped bamboo materials in a width direction so that the top surfaces and under surfaces of these bamboo materials are alternatively inverted. A plurality of these joined plates are laminated to form a plywood-panel. The plywood-panel is joined in the width direction to form the shell.
A shell of a drum disclosed in Japanese Examined Utility Model Application, Second Publication No. S53-47939 is formed by joining long thin single-panels in a cylindrical shape.
Conventionally, in a drum made of plywood, the shell is basically formed by enclosing a single-panel having low specific gravity between single-panels having high specific gravity. Known examples of a shell formed by enclosing a single-panel having low specific gravity between plywood-panels having high specific gravity include maple (specific gravity: 0.7)+poplar (specific gravity: 0.45)+maple (specific gravity: 0.7), mahogany (specific gravity: 0.65)+poplar (specific gravity: 0.45)+mahogany (specific gravity: 0.65), and birch (specific gravity: 0.71)+meranti (specific gravity: 0.55)+birch (specific gravity: 0.71).
The reason that a single-panel having high specific gravity is used for the outer side is that this reduces the effects of changes in air temperature and climate, while maintaining the external appearance by increasing the strength of the outer surface and reducing problems such as damage and abrasion.
However, in a shell formed by enclosing a single-panel having low specific gravity between plywood-panels having high specific gravity, since the outer side of the single-panel having low specific gravity is pressed by the single-panel having high specific gravity, there is considerable loss of vibrational energy due to internal abrasion. This leads to problems that the vibration of drum is rapidly attenuated and the volume becomes relatively small.
Each of the drums disclosed in the references mentioned above has advantages and disadvantages that leave room for improvement. In the Japanese drum disclosed in Japanese Unexamined Patent Application, First Publication No. H11-45087, the tensile structure of the drum head has a special structure, and a conventional head frame cannot be used. The drum disclosed in Japanese Patent Publication No. 3324577 requires many steps to manufacture the bamboo plywood, increasing the manufacturing cost. As for the drum disclosed in Japanese Examined Utility Model Application, Second Publication No. S53-47939, when the shell is made using long thin single-panels, there is noticeable warping and the like due to drying and aging of these single-panels, and gaps are liable to appear between them.